Dan mounted the TV on a board that he hinged with gas springs so it would be easy to open and close when necessary. Additional space in the compartment is accessible from a panel on the other side of the wall that's totally inconspicuous when closed.

Dan, you're welcome over to my apartment any time. Just please bring a set of tools and some gas springs with you.

UPDATE: Reader Matthew (and several commenters) point out that this would be a major code violation in many areas. So know that before you start knocking down walls. [Apartment Therapy via Lifehacker]